求教，关于xdf教程里面的语法题！

Although it claims to delve into political issues,television can be superficial such as when each of the three major networks broadcast exactly the same statement from a political candidate.

a.superficial such as when each of the three major networks

b.superficial,as can sometimes occur if all of the three major networks

c.superficial if the three major networks all

d.superficial whenever each of the three major networks

e.superficial,as when the three major networks each

答案是e，请教这句话应该怎么翻译，e中as是什么词性，做何讲？

另：关于xdf教程里面的题目，cd里面有没有解释、讨论？

找得好累。。